The present invention relates to a fuel injection controller and a fuel injection control method for an internal combustion engine.
In an internal combustion engine mounted on a vehicle, for example, a fuel injection control is performed in the following manner. The control involves calculating a fuel injection amount that is an amount of fuel to be injected from the injector and an injection starting point of time for starting the injection based on the operation state of an internal combustion engine (such as the speed and load of the internal combustion engine). Subsequently, the control involves calculating an injector energization time required for fuel injection of the calculated fuel injection amount as an injection time based on fuel pressure that is the pressure of fuel supplied to the injector. In the control, as a result of the energization being performed for the injection time from the injection starting point of time, the injector performs fuel injection.
The calculation of the injection starting point of time and the injection time is performed prior to the implementation of the fuel injection. Thus, between the point of time for calculating the injection time and a point of time for starting the fuel injection, there is a difference in time to a certain extent. On the other hand, the fuel pressure constantly changes due to factors such as fuel feeding by the fuel pump and pulsation in the fuel supply passage. Therefore, the fuel pressure generated when the fuel injection is actually started may be different from the fuel pressure of the time when the injection time is calculated. In such a case, there may occur an error in the fuel injection amount.
To resolve this, in Japanese Laid-Open Patent Publication No. 2001-336436, a fuel injection controller is disclosed. The fuel injection controller predicts the fuel pressure at the fuel injection point of time based on movements of the detected fuel pressure value up to that point of time and corrects the injection time of the injector based on the predicted fuel pressure.
However, in the above conventional fuel injection controller, when there is an error in the predicted fuel pressure, there also occurs an error in the fuel injection amount corresponding to the error. Thus, there is a limit determined by the accuracy of the prediction of fuel pressure to the improvement of the accuracy for the injection amount of the above conventional fuel injection controller.